An aerial device known as a parafoil has been used successfully both for captive flight and free drops. In the captive flight mode, the parafoil may be utilized to suspend a payload in the atmosphere, the payload perhaps being a scientific instrument or other object. The parafoil can also be used in place of a parachute for return of a man or a load from the atmosphere or from space. An advantage of the parafoil is that it is relatively easy to achieve directional flight to a considerably greater extent than with a normal parachute. Such a parafoil is described and claimed in U.S. Pat. No. 3,285,546 issued to the present inventor on Nov. 15, 1966.
However, the parafoil is dependent for successful operation on high relative winds. The parafoil has an air foil shape which to be completely effective requires high relative wind. In the absence of such wind, it is a simple deceleration device, depending entirely on a flat bottom surface for glide.
The parafoil relies on a ram air scoop to keep it inflated. For cargo drops at very high speed, the cargo acts as a pendulum which swings back and forth during descent of the parafoil. If the cargo swings too much, the ram air scoop action is lost and the parafoil can collapse in these circumstances.